A control unit is described in European Patent No. 376983 which is preconfigured for performing a plurality of functions and which, after being installed in the vehicle for the first time, is configured according to the functions needed in the vehicle in response to an activation command. Unneeded functions remain inactive. The control unit can be used as a universal control unit for a wide variety of vehicle types. However, the basic fact that available, yet non-activated, functions are provided generally makes it possible for unauthorized personnel to expand the original range of functions supplied by the manufacturer and, for example, to use components that are not approved by the manufacturer. All that is needed to do this is to manipulate the non-volatile memory in which the valid control unit configuration is stored.